US 2012/203225 A1 and U.S. Pat. No. 5,888,197 describe devices for orthopedic fixations comprising two or more frames which can be arranged next to a limb and are connected by a rod fixed to the frames by means of a locking mechanism comprising two jaws which can be closed by a cam mechanism provided with a lever to tighten a locking mechanism to a portion of the frame. The frames of these known devices, being formed by straight bars, cannot be arranged around a limb, in particular to arrange wires, bars or nails in a radial configuration with respect to this limb, as it is instead necessary in the Ilizarov apparatuses. The jaws also exert a force perpendicular to the axis of the frame to which are tightened, then a force which is not prevalently axial.
US 2013/0018374 A1 describes a device for orthopedic fixations comprising two frames of annular shape that can be arranged around a limb and are connected by a plurality of rods fixed to the frames by means of locking mechanisms comprising two jaws which can be closed by a cam mechanism provided with a lever. These jaws do not tighten the frames but bring near two pins which are inserted in corresponding longitudinal holes formed in the frames to prevent the sliding of a locking mechanism around a frame, otherwise possible through a screw kinematic mechanism.
This known device has a relatively complex structure which makes the device expensive and complex to use. In addition, the operation of this known device requires the presence of many metal parts that make the same device heavy and opaque to X-rays, so as to adversely interfere during radiological examinations. Moreover, the rods may be fixed only in a limited number of positions corresponding to the number of holes formed in the frames, so as to prevent a precise application of wires, bars or nails in a radial configuration with respect to the limb, as is instead required in the Ilizarov apparatuses.
DE 40 13 822 A1 describes a device for orthopedic fixations comprising two frames of annular shape that can be arranged around a limb and are interconnected by a plurality of rods fixed to the frames by means of a screw locking mechanisms that apply an axial force on a frame but also make difficult its use in a medical field because of the opacity to X-rays of the screws and of the relative complexity and slowness of their tightening in critical situations.